Planar THz electromagnetic graphene pass-band filter with low polarization and angle of incidence dependencies

Abstract

We propose and analyze a graphene electromagnetic filter for the terahertz (THz) region. The filter represents a planar square array of graphene elements. A unit cell of the array is formed by two coaxial graphene rings placed on the opposite sides of a thin dielectric substrate. The two electromagnetically coupled rings resonate with dipole plasmonic modes. The rings have slightly different dimensions and consequently different yet close individual resonant frequencies. At a frequency lying between these two resonances, the currents in the two interacting rings have opposite directions. This leads to a suppression of the reflected from the array waves and consequently to a high transmission through the array. For the chemical potential of the graphene μ_c=0.6 eV, the calculated quality factor of this resonant mode is Q=5 at the frequency f=0.8 THz. At this frequency, the reflection coefficient of the array equals -36 dB and the transmission peak which is defined by the graphene losses is -1.8 dB. We show that the frequency position of the transmission peak can be varied in a wide range by the graphene chemical potential.

Tunable dual‐band filter based on monolayer black phosphorus

“…For a change of the polarization angle to $$\phi $$=$$4{5}^{\circ }$$ (see Figure 3B), the spectra exhibit two minimum transmittance peaks with resonant frequencies at 31.81 and 50.04 THz with a transmittance of 69% and 46%, respectively (blue solid line). The proposed filter is considered reciprocal, as a consequence, its S‐parameters are given by the relation: $$| \,{{\rm{S}}}_{{11}}{| }^{2}\,$$= $$| \,{{\rm{S}}}_{{22}}{| }^{2}$$ (reflectance) and $$| \,{{\rm{S}}}_{{12}}{| }^{2}$$ = $$| \,{{\rm{S}}}_{{21}}{| }^{2}$$ (transmittance) 23 . Thus, excitation of the resonant modes in the BP plane depends on the polarization angle, therefore, this effect can be used in practical applications.…”

Theoretical Study of Plasmonically Induced Transparency Effect in Arrays of Graphene-Based Double Disk Resonators

“…The influence of inter-band transitions can be neglected in the considered operating frequency range, since the condition ħω<<2µ c is satisfied [11]. Therefore, the following formula derived from Kubo formalism [6] can be used for the calculation of σ g : where ω is the angular frequency, e is the charge of electron, k B is the Boltzmann constant, Tis the temperature (300 K), ħ is the reduced Planck constant, Γ is the scattering rate (0.1 meV), and μ c is the chemical potential.…”

“…In this context, graphene emerge as an interesting alternative. High rigidity, good thermal and electrical conductivity, presence of plasmon resonances, and dynamic control of its physical properties by electrostatic and magnetostatic fields are some of the outstanding features of its two-dimensional structure [3]- [6]. These features enable the use of graphene, for example, in the design of field effect transistors (FETs) [7], photodetectors [8], and antennas [9].…”

A Tunable Graphene 0–90° Polarization Rotator Achieved by Sine Equation Voltage Adjustment

“…Recently, various periodic metasurface applications achieved absorption [1,2], filter [3], sensing [4] and polarization conversion [5]. In these applications, polarization conversion holds the freedom to wave propagation and information processing.…”